Ph I study of cancer chemotherapy of All-trans-retinoic acid (ATRA) metabolism in hormone-refractory prostate cancer. ATRA is known to induce its own metabolism but the drug metabolizing enzymes responsible for this are not well characterized. Auto-induction will be investigated in a 3 phase study using the Pittsburgh cocktail to evaluate selected drug metabolizing enzyme activity in patients w/prostate cancer. Drug metabolizing enzyme phenotyping will be done simultaneously with ATRA pharmacokinetics on Day 1 & 14 of daily dose of ATRA.